You could try and take it back and claim under warranty but Apple will know it's been damaged by water.
I'm not sure whether there's a water indicator like on the iPhone. If you look down the headphone jack (the actual hole- you may need a torch), and it's got a pink spot at the bottom then your toast. There are ways to cheekily get round this, you could put some bleach on something small enough and bleach it white again and try and take it back.
just try to open it up and let it dry out my ipod wznt even water dmg and i had to call and send it in 3 times before they finally gave me a new 1 if u ipod wznt in water 4 long your ipod might b a lil jacked up but still useable if u dry it out